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Overview
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Anaphylaxis
Contents
Overview
Treatment
Prevention
Anaphylaxis is a severe and potentially life-threatening reaction to a trigger such as an allergy.
Important:
Coronavirus (COVID-19)
At the moment it can be hard to know what to do if you're unwell.
It's still important to get medical help if you need it.
Do not delay if you feel very unwell or think there's something seriously wrong. Call 999.
Symptoms of anaphylaxis
Anaphylaxis usually develops suddenly and gets worse very quickly.
The symptoms include:
feeling lightheaded or faint
breathing difficulties – such as fast, shallow breathing
wheezing
a fast heartbeat
clammy skin
confusion and anxiety
collapsing or losing consciousness
There may also be other allergy symptoms, including an itchy, raised rash (hives); feeling or being sick; swelling (angioedema) or stomach pain.
What to do if someone has anaphylaxis
Anaphylaxis is a medical emergency. It can be very serious if not treated quickly.
If someone has symptoms of anaphylaxis:
Use an adrenaline auto-injector if the person has one – but make sure you know how to use it correctly first.
Call 999 for an ambulance immediately (even if they start to feel better) – mention that you think the person has anaphylaxis.
Remove any trigger if possible – for example, carefully remove any stinger stuck in the skin.
Lie the person down and raise their legs – unless they're having breathing difficulties and need to sit up to help them breathe. If they're pregnant, lie them down on their left side.
Give another injection after 5 minutes if the symptoms do not improve and a second auto-injector is available.
If you're having an anaphylactic reaction, you can follow these steps yourself if you feel able to.
Read about how to treat anaphylaxis for more advice about using auto-injectors and correct positioning.
Triggers of anaphylaxis
Anaphylaxis is the result of the immune system, the body's natural defence system, overreacting to a trigger.
This is often something you're allergic to, but not always.
Common anaphylaxis triggers include:
foods – including nuts, milk, fish, shellfish, eggs and some fruits
medicines – including some antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin
insect stings – particularly wasp and bee stings
general anaesthetic
contrast agents – dyes used in some medical tests to help certain areas of your body show up better on scans
latex – a type of rubber found in some rubber gloves and condoms
In some cases, there's no obvious trigger. This is known as idiopathic anaphylaxis.
Preventing anaphylaxis
If you have a serious allergy or have experienced anaphylaxis before, it's important to try to prevent future episodes.
The following can help reduce your risk:
identify any triggers – you may be referred to an allergy clinic for allergy tests to check for anything that could trigger anaphylaxis
avoid triggers whenever possible – for example, be careful when food shopping or eating out if you have a food allergy
carry 2 in-date adrenaline auto-injectors at all times – give yourself an injection whenever you think you may be experiencing anaphylaxis, even if you're not completely sure
Read more about preventing anaphylaxis
Page last reviewed: 29 November 2019
Next review due: 29 November 2022
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